And, intention, I realise that much of what I say about your graph’s “straight lines” might need clarifying:
Overall, from 1850 onwards, they are exponential (curved towds the vertical), not staight. I’m talking about the apparently straight portions of those graphs after, say, 1980.
For the sake of argument, let’s set aside the possibility of the blue line rising exponentially (ie. the emission rate increasing) from now on, and keep the rate (ie. the current steepness) constant. (Yes, we are also setting aside future emission-reducing efforts here, too)
Let’s also, for argument’s sake, set aside my concerns about deforestation, desertification and acidification affecting the sequestration rate (ie. anything that makes the orange line less steep).
If the orange line’s steepness (ie the sequestration rate) stays constant from now on, it will not prevent the red line pushing up to levels of 800+ ppmv unless the blue line changes, agreed?
The only way such a peak will be prevented is if the blue line continues at the same steepness but the orange line gets much steeper, agreed?
Are you suggesting that the orange line wil get much steeper (ie. the sequestration rate will not only avoid a decrease but actually increase massively) over the coming decades?
How much more plainly can we put this to help you understand.
We have ample evidence that a mechanism exists which is capable of removing 30-60ppm CO2 increases form the atmosphere within a century. Even you don’t seem to dispute this fact.
We do not know what the mechanism is, We simply lack that information. As scientists we therefore cannot talk about the mechanism. It’s not a case of reluctance. It is a case of lacking sufficient information to engage in the conversation.
This is akin to accusing you if being reluctant to talk about the depolarization initiation in heart function. You know that your heart does function by electrical depolarization. You’ve seen it on an EKG. But you lack the knowledge to talk about the mechanism that causes it.
That doesn’t make you a fool or dishonest or reluctant to talk about it. You are simply unable to talk about it because of lack of knowledge despite having ample evidence that such an event has occurred and will occur again.
Do you understand now? Science isn’t about talking smack on subjects about which you lack basic information. Science is about discussing facts. In the specific case of the causal mechanism of the proven large scale, rapid sink case we lack facts, so the discussion is of themechnism is necessarily limited.
Of course not. You shouldn’t believe anything without evidence, and that includes AGW. If you choose to believe that things will be different his time then by all means do so, but acknowledge that such a belief has been adopted despite a gross ignorance of the carbon cycle and precisely what mechanism has allowed the atmosphere to remove such massive fluxes rapidlyin thepast.
IOW you might be right, but there’s no evidence to support such a contention.
35% of what?
The rise started in 1600, is that your starting point? If so then doesn’t this immediately rule out a significant human involvement? And if 1600 isn’t your starting point then what was the relative rise between 1600 and whatever tour starting point was? If you can’t answer that then what exactly does “35%” tell us?
Again, compared to what? What should the temperature rise have been, and how did you calculate this? Surely you aren’t suggesting a simple linear relationship between CO2 levels and temperature? Yet it appears the only way to gauge whether the temperature rise has been more or less dramatic than it should have been is to engage in circular reasoning concerning the impact of CO2 increases in global temperatures.
How do you know this? Given the level of uncertainty of short term temperature fluctuations in the past, and given that “the phase relationship between CO2 and [ice core] temperature previously inferred for the start of the last deglaciation (lag of CO2 by 800±600 yr) seems to be overestimated”* how do you know it isn’t exactly the same as past CO2 rises?
Why is it mystifying that I don’t believe something for which you have absolutely no evidence in a field in which there are massive uncertainties about the basic mechnisms.
Err, no, where the hell did you get that?
WTF? This is a total Red Herring.
You start out suggesting that fossil fuel formation has been the missing sink that explains past rapid 30-60ppm CO2 concentration declines. Then when I point out that the fact that it is impossible you start talking about fossil fuels as a source.
Can you please try to keep your argument straight. Do you believe, as you suggested, that fossil fuels contribute to the rapid massive past sinks, or not?
No.
There is another number, 42. There are a whole universe of numbers. The question wasn’t whether you could find some random numbers. The question was whether you could put a number on your hypothetical certainty. And you can’t.
Once gain, you’ve introduced a massive red herring. Please try to keep the argument on one track.
No. That; just silly. The trend was exponential from 1600-1750. It continued to be exponential from 1750-2009. Why assume the human contribution is significant if it hasn’t altered the trend by one iota?
It could.
An it could have a significant anthropogenic component decreasing the steepness of the exponential curve too.
But until you have evidence to this effect then you are just engaging in wild speculation, not raising legitimate concerns. Do the science, show me the statistics that show with a 95% probability that the curve shape has changed as a result of human intervention and we will have something to discuss. Until then it’s just alt-history speculation and nothing more.
But we know that the proposed “solutions” to this problem will have irreversible impacts on humans beings. You don’t dispute this. So why pretend that we can just “grow another head” after we’ve cut this one off?
Much like your entire positioning this thread really. Fact after fact is introduced demonstrating that every6 single contention you have made from your very fist sentence is completely wrong, and yet you keep arguing that “maybe” there is a cause for panic despite any evidence at all, because you have to think of the children.
That’s pretty fuckin’ stupid.
Yes, that is pretty much my response to you. You clearly don’t; know the facts or the levels of uncertainties actually involved here. That much is apparent just from your OP. The fact that you had to reduce you alarmism to “Won’t somebody please think of the children simply drives the last nail into the coffin. It is indeed merely the attention-seeking alarmism du jour.
once again you demonstrate a gross ignorance of the facts. These tropical “forests” are mostly savanna woodlands, not the rapidly disappearing tropical forests. And thanks to bush encroachment these tropical woodlands are growing at avast rate.
How the fuck did you think that shrinking forests were acting as a massive sink? That’s pretty fucking stupid.
Loulergue et al 2007 “New constraints on the gas age-ice age difference along the EPICA ice cores, 0–50 kyr” Clim. Past, 3,
Why can’t the mechanism solely involve forests, soil, plankton and limestone though? I don’t understand why you seem to be insisting on introducing some mysterious Invisible Sink when Ockham’s Razor points directly to those rather mundane sequestration mechanisms that we know about.
But I can see how those mundane mechanisms I mentioned could rapidly capture up to 60 ppmv per century if the Earth were as it was before humans came along. And after we reach peak CO2 (whatever the peak turns out to be) I can see how the Earth as it is now could sequester CO2 faster than I thought. What I cannot see is how the Earth as it is now can sequester CO2 fast enough to counteract the rapid depletion of sequestered stores that humans are undeniably engaging in. Even 60 ppmv per century is still much slower than the 170 ppmv per century we are adding. Surely your Invisible Sink will have to kick in soon with a Uniform sequestration rate of an additional 110 ppmv per century to prevent the CO2 concentration rising further?
But there surely is evidence that the current situation is simply different to those past events? There simply aren’t as many forests, and the underground hydrocarbon stores simply have been burned in their Gigatons.
Why do you say 1600? Looking at the Law Dome you cited before, one clearly has a fair bit of latitude to fit a curve even ignoring error bars. If 280 ppmv represents the rough background level, it is only nearer 1800 that any exponential curve pushes through this: “a 35% increase on 1800 levels” is a perfectly reasonable way to describe the increase. I really don’t understand how you can deny obvious human influences after 1800 by pointing to a few 1600 data points.
Compared to the clear and obvious temperature rises that preceded the CO2 rises in the past, as you yourself conceded: “We simply don’t know what drove these rapid shifts in atmospheric CO2 levels, except that they seem to be caused by an increase in temperature, or at least they followed increases in temperature.” Are you now retracting this bolded statement?
There is no evidence that humans have dug up Gigatons of hydrocarbons and burned them? How could I convince you of this?
You said “So in other words if something for which there is shaky evidence is actually occurring, and something else which we know does occur but don’t understand, operates by the mechanisms you postulate it works by, despite having absolutely no evidence whatsoever, and if it is no longer able to operate by those mechanisms which we have no reasons to believe even exist…”. Bolding mine
Really? Where?
How is wanting AGW-accepters predictions to come true not misanthropic?
But 500 Gigatonsisn’t pulled out of thin air – it’s a pretty straightforward account of how much hydrocarbons we’ve burned and forest we’ve cleared in the last few centuries, and even intention’s graph demonstrates it clearly. Really, your “scientific” fence-sitting on this particular point is beginning to look like anything but.
So you’re saying that humans might have emitted not 500 Gigatons, nor even, say 250 Gigatons, but maybe only 50 or so? You realise that you are calling even people like intention liars here?
How? How are humans demonstrably removing Gigatons of carbon from the atmosphere?
OK, I’m willing to go with you on this one even if it involves a fair bit of work on my part. I would start by agreeing on an estimation of how much CO2 would be produced by burning a metric ton of hydrocarbons. Do you think we might come to agreement here? Then I would estimate how many such tons have been burned to date. Do you think agreement might be reached here also? I’ll tell you the steps thereafter when we come to them, but are you happy to embark on the first two, at least?
I do dispute it.
I’m glad you consider my satire of your position so accurate.
The report states: “Despite rapid deforestation, Stephen’s team also showed that tropical forests are the net source of a mere 100 million tonnes of carbon annually, contrary to previous estimates of 1.8 billion tonnes. This suggests that carbon sequestration in the tropics is substantial enough to almost counterbalance the effects of deforestation.”
Read the report again. Though they are shinking, tropical forests are a bigger sink than previously believed. In any case, why are you even deigning to discuss such mechanisms? They’re complete mysteries beyond the ken of us all, are they not? Blake, you are an intelligent chap, and I dare say your contributions have changed my mind in the past on some issues. But by my count you are the only Doper who refuses to accept that humans have burned enough hydrocarbons to contribute significantly to the current CO2 concentration. Refusing to accept that such elevated concentrations will have negative consequences I can understand, though I might disagree. Are you willing to accept that going through the “accounts” might, in principle change your mind on this issue, or is it futile of me to even start?
The sheeple may regret hopping aboard the ‘nouveau environmentalist’ bandwagon once they feel the painful **$**ting of what would once have been a garden variety, facile refrigerant gas leak repair in their humble home fridge or A/C, become a write-off level expense as a direct result of sky-rocketing hydrocarbon production costs.
SentientMeat, thanks for your posting. As you say, we have few areas of disagreement. These are:
I think that the earth’s temperature has an upper limit. This limit is set by cumulus and cumulonimbus, which form when the temperature rises and cool the earth. As I mentioned before, I discuss this in detail here.
Despite historically rising temperatures in the Arctic and the temperate zones, there is very little historical change in the temperature in the tropics. Most of the poor live in the tropics. Thus, the allegation that rising temperatures will hit the (tropical) poor hardest is not borne out by the data.
You say:
I applaud your concern for the earth’s poorest citizens, who are legion. It is a credit to you. However, the best way to ameliorate future suffering from climate is to ameliorate current suffering from climate. That way, whether the earth is warming or not, suffering is sure to be ameliorated. Not only that, suffering will be ameliorated from today forwards into the future, every day, every year. Your way, on the other hand, says to the poor “well, you’re just gonna have to grin and bear it for a quarter century or so, sorry, can’t help you, can’t help your kids, but there’s a chance we might possibly help your grandchildren … maybe.”
If we take your path and after a half century it proves to be ineffectual, saying that you tried and that you wasted billions of dollars and that you didn’t ameliorate a damned thing is not going to impress the poor.
For example, Kyoto has already cost untold billions. Even Kyoto supporters agree that if every Kyoto signatory met their targets (ain’t gonna happen, but we can dream) it will lower temperatures in 2050 by less than 0.1°C … be still my beating heart. Surely you can’t seriously claim that this is helping the poor? …
(PS – please, please don’t tell me that Kyoto is only the first step. If the first step costs untold billions and achieves a 0.1° temperature cooling, I’m afraid that the second step will bankrupt the planet for a meaningless half a degree of cooling. Half a degree of cooling will put us back into the climate of about 1900 … which as far as I can see is a meaningless change. I don’t think the poor were overjoyed in 1900 to be half a degree cooler, in fact, I doubt if they noticed …)
(PPS – in winter, a number of the poorest people in the US make their way south where it is warmer. Perhaps we could spend some of the Kyoto money educating them that cooling is actually good for the poor, they don’t seem to have noticed that …)
SentientMeat, thanks for the question. I’ve never said that the sequestration of CO2 will keep the atmospheric levels (red line) from increasing unless emissions level off.
What I have said is that if emissions were to magically level off at the current rate of about 8 gigatonnes of carbon (GtC) per year, that the atmospheric rate would not continue to rise indefinitely. Remember that the sequestration rate is not related to the rate of emissions, but to the atmospheric CO2 level. As atmospheric CO2 increases, so does the sequestration rate. As a result, if emissions magically stayed level, eventually the atmospheric CO2 will level off as well. Depending on your assumptions about e-folding time, with current emission levels, this would be at about 450 - 500 ppmv.
To answer your question, it seems there is some misunderstanding of the graph. It shows cumulative emissions, sequestration, and additions to the atmosphere. If a cumulative graph has a straight line up to the right as you posit, that means that emissions are level at the current rate, not increasing.
And if emissions are level at the current rate, no, we’ll never get to 800 ppmv.
Hope this makes it clear, if not, please let me know.
Are you trying to wind me up? How many fuckuing times do I have to repeat the same fuckingpoiint?
We do not know what the mechanism is, We simply lack that information. As scientists we therefore cannot talk about the mechanism. It’s not a case of reluctance. It is a case of lacking sufficient information to engage in this conversation.
You do not have sufficient information to engage in this conversation, I do not have information to engage in this conversation. Nobody has sufficient information to engage in this conversation.
Get it? The mechanism could solely involve forests, soil, plankton and limestone. It could solely involve unicorns, pixies, gods and candyfloss. We3 don’t fucking know. However you insist that it must solely involve forests, soil, plankton and limestone, and then you build your entire sky-is-falling screed on the fact that such processes can’t continue indefinitely.
You are panicking about an unproven assertion based on a hypothetical failure of an unproven mechanism for an event that you don’t remotely understand. It’s a chicken little argument from ignorance on a colossal scale.
Because we do not know what the mechanism is, We simply lack that information. As scientists we therefore cannot talk about the mechanism. It’s not a case of reluctance. It is a case of lacking sufficient information to engage in this conversation.
How many times do I have to repeat this point?
Then publish your argument. If it’s sound you will get printed in GCB at the very least, probably in Nature. Because I’ve seen real scientists publishing on this topic for over 15 years and they can’t produce any argument to this effect that even convinces one another. So consider me skeptical that you’ve single handedly resolved this problem.
Oh well, that’s convinced me that we should panic and strip billions of their rights and commit tens of billions of unrecoverable money to the problem that might not exist. It’s an argument form ignorance, why didn’t you say so in the first place. You can’t explain how it might work so it must be so.
Since you started this thread claiming that the level had in fact been stable for the past 2000 years I find your reliability on those topic to be questionable. But assuming this figure is correct, so what? What is the upper level? Intention has already demonstrated that emissions are not increasing, so what is your reason for believing that they will continue to rise?
All events are different to past events. This one of s no differently different.
You are joking, right? There are more forests now than at the last glacial maximum? Can we have a cite for this claim?
Because 1600 is where the level started unambiguously rising.
WTF does “rough background level” even mean? And since you’ve acknowledged that past fluctuations of 30-60ppm were common how did you determine this? And what is the relevance of this anyway?
OK, then let’s describe it as a 1% increase over 2005 levels instead. You seem to be engaging in circular logic, by selecting the date that you think human influence changes things, and then using that as your desired baseline to prove that human activity changes things. That has no validity whatsoever and can be dismissed out of hand.
What do you mean “a few points”? There are only fewer points between 1600 and 1750 then between 1750 and 2009 because the fricken’ timescale is shorter.
So I ask for the 5th time: what is this based on? How did you establish that past rises more clearly and more obviously preceeded CO2 rises? You keep ducking and weaving around this question and refuse to answer it.
It’s quite a simple question, so why not just answer it? How did you determine that past temperature rises clearly and obviouslypreceded the CO2 rises, but that the current rises clearly and obviously did not?
Oh god, put the straw away. I never posted anything even remotely like this.
You said “So in other words if something for which there is shaky evidence is actually occurring, and something else which we know does occur but don’t understand, operates by the mechanisms you postulate it works by, despite having absolutely no evidence whatsoever, and if it is no longer able to operate by those mechanisms which we have no reasons to believe even exist…”. Bolding mine
Me: So what I’m asking you is what evidence I could collect that would convince you that this isn’t just another one of those short term CO2 increases?
You: Rapid planet-wide fossil fuel-store formation would set my mind at rest nicely, thanks.
So pray explain, what the fuck did you mean by when you said that a “rapid planet-wide fossil fuel-store formation” would convince you that the current increase is another short term event, if you weren’t arguing that “rapid planet-wide fossil fuel-store formation” were reaponsible for the rapid short term sink in the past?
Honestly, I want an answer to this question. Because the only two possible explanations I cans see are:
You can’t follow your own argument or
You want evidence for something happening now that you know has never been possible in the past.
IOW you are either being a disingenuous Chicken Little or presenting an argument so fucking stupid that even you can’t make sense of it.
Because it doesn’t evidence a dislike, distrust, contempt, or hatred of the human species.
Yes, and?
No, it isn’t.
More straw.
Gee, that’s going to be quite the Guy Fawkes bonfire, isn’t it?
Geez, I can feel the heat from here.
Good.
It’s your methodology, do as you see fit. I can only judge the thesis on the final product.
So you dispute that people have been prevented from cutting down trees on their own land because of the threat of AGW? Or do you dispute that this prevents them from enjoying their own property And gaining maximum benefit from it?
I hope you say yes, because this is so trivially easy to prove that it will allow me to dismiss your entire line of argument on this issue. Of course if you say no then you are going to demonstrate how you will reverse these changes and give these people their enjoyment back if, in 50 years time, we discover you are wrong.
If that was meant to be my position it wasn’t a satire. I do believe your cries to be simply the alarmist doomsaying du jour.
Yes!! A thousand times, yes.
Almost counterbalance. Tropical forests are demonstrably not the missing sink because basal area increase doesn’t even counterbalance the emmisons for deforestation.
Oh FFS your own quote shows that they are not a sink at all. The rate of sequestration doesn’t even equal the rate of emissions from deforestation.
More straw.
Oh an argument ad populum. Consider me convinced
What “accounts”? What are you talking about?
Look if you have evidence bring it to the table and let us examine it. If all you have is “We’ve done x, surely it *must have resulted in y” then don’t bother. I’ve heard it before.
I rest my case that AGW deniers and AGW devotees belong, psychologically, to something closer to cults than any dispassionate rational analysis. It is simply not possible for members of these groups to chill out any more than it is possible for the Hare Krishna or the Mormon to sit idly by while the world remains unenlightened or heads straight for hell.
intention, let me say that I find it hugely gratifying that we have come to understand and respect each other’s position here, such that we can identify our agreements and disagreements with such precision. I apologise for the initial snarks – please understand that they were designed to get you involved here since I value your contributions so highly.
If you remember, there were three ways in which my concerns could be allayed. I wished to be convinced that:[ul] the CO2 concentration is rising almost entirely naturally, or [li]some natural carbon-sequestering mechanism will kick in cause a level off of 500 ppmv or less, or [*]500+ ppmv concentrations won’t have significant consequences any old how. [/ul][/li]You, and everyone else here bar one, seem to have no problem agreeing that the first possibility is so remote as to be unconvincing in the extreme. The third possibility is an entirely reasonable point of debate (though I would say that even increased cloud cover is a fairly significant consequence, even if it prevents significant temperature rise).
The second point is what we’ve been discussing in much detail thanks to your graph. You seem to be of the opinion that the orange line will bend towards the blue line in future:
That this has happened to date is welcome news to me. However, I do not see how you can be so certain that this will continue to be the case.
Discussing whether deforestation, ocean acidification and the like would cause the rate to slow down was something of a distraction here, and I’m happy to set this possibility aside for now. But to simply assume that the orange line will bend ever closer towards the blue just seems unrealistic in the extreme to me. I laid a ruler on the blue line of your graph, such that it continued straight at its current steepness. The question then is, what would the orange line need to do to meet it?
If you take your mouse and roughly continue the orange line’s exponential curve from 1850 through 2000 and on into the future, one guesses that it will curve up and meet the straight blue line some time next century. That is when emissions=sequestration and the red line (atmospheric concentration) will not increase further.
But at that point, the orange line is not far off vertical! The sequestration rate would be skyrocketing every year! When one considers the actual sequestration mechanisms – the forests, soils, plankton and whatnot – it’s difficult to see how they could sequester twice as much carbon per year, or more, than they currently are. (I make the orange line more than twice as steep as it is now when it meets the blue line.)
And my concerns don’t end there. Even if this happens, the gap between the blue and orange lines has not by any means reached its maximum yet. I estimate the gap to reach a maximum in around 2060, such that the vertical distance between the blue and orange lines is more than twice what it is now, meaning that atmospheric concentration would be increasing much more rapidly than the current 1.7 ppmv per year. Does all of this sound reasonable to you?
Like I said, even if that’s the case, I’d still call such consequences “significant”. I’d hope that negative consequences of such cloud cover would be minimal. (Is there any evidence that cloud cover is increasing, by the way?)
Actually, my concerns about negative impacts on the tropics were more to do with rising sea levels from melting land-based ice and thermal expansion, hence my OP’s example of Bangladesh. Of course, I hope that the time lags involved would give us time to invest in flood defences if it really did seem like this was inevitable (and it wouldn’t be if temperatures didn’t rise further first).
intention, I’m afraid you underestimate my typical liberal hand-wringing by many orders of magnitude :). I agree completely. Of course, all I do sitting here in my comfortable, temperate life is donate to Third World First and advocate greater and more sensibly-spent aid and investment in the infrastructure of countries I’ve merely visited on holiday, hypocritically chugging huge quantities of IR-absorbing gases into the air on my way. You, on the other hand, live and work in these countries, immersing yourself in their peoples’ lives and problems in a way which inspires in me only shame and the greatest admiration.
This thread shows the best of the SDMB. When I describe you as “climbing aboard” I do not mean that you and I are in agreement on every issue, but that we are speaking amicably as friends and respect each other’s position. On that score, I wonder whether you could help me out? As you can see, I’m having trouble convincing brother Blake about human influences on the CO2 graph. Would you be willing to step on the AGW-accepter deck on this particular issue in order to point out where my strategy could be more effective?
But soils, forests plankton and the like are clearly significant carbon-sequestering mechanisms, agreed? Why can’t we even talk about the possibility that they are all that is necessary to posit in an Ockham’s Razor sense?
But the former is more likely, agreed?
No, I ask why it can’t solely involve them.
Oh, relax, it will all be economically peachy. Even if you show that an economic downturn followed such measures, it’s entirely possible that they are economically beneficial and that the downturn would have been even worse without them.
Actually, no, he says that future emission rates are impossible to predict, and accepts that an increasing emission rate (from China and India’s future contributions, say) would lead to upper levels of double or even triple the 1800 level.
No, it’s pretty ambiguous – you can fit the curve in all manner of ways even if you ignore the error bars on those data points. You say 1600, I say 1800: Tomato, tomahto.
OK. How much of this increase since 2005 do you think is due to the thousands of power stations around the world demonstrably burning Gigatons of coal and all the other CO2 producing activities that billions fo humans engage in?
Well, no, the OP referenced the Manua Loa measurements because they are direct, not by proxy: there simply are more data points the later you go along the graph.
Well, how about your very own words? “We simply don’t know what drove these rapid shifts in atmospheric CO2 levels, except that they seem to be caused by an increase in temperature, or at least they followed increases in temperature.” What did you base this on, might I ask?
SentientMeat: I’m saying that’s because, this time, humans have dug up Gigatons of buried stores and burned them. That you find this so unreasonable a suggestion is mystifying. Blake: Why is it mystifying that I don’t believe something for which you have absolutely no evidence in a field in which there are massive uncertainties about the basic mechnisms. SM: There is no evidence that humans have dug up Gigatons of hydrocarbons and burned them? How could I convince you of this? B: Oh god, put the straw away. I never posted anything even remotely like this.
Yes, I do. Like I said, this would set my mind at rest.
But wanting negative consequences to come to pass does evidence such dislike, does it not?
So you agree that 500 Gigatons is a fairly accurate account of how much CO2 we’ve emitted? If so, how can such a huge addition not affect CO2 concentrations?
OK, how many Gigatons of CO2 would you be willing to accept that humans have emitted?
Blake: And it could have a significant anthropogenic component decreasing the steepness of the exponential curve too. SentientMeat: How? How are humans demonstrably removing Gigatons of carbon from the atmosphere? B: Geez, I can feel the heat from here…
OK, burning a ton of lignite emits 2.8 tons of CO2. Agreed?
They’ll get all their enjoyment back when they’re allowed to burn their trees and spend the extra money gained by the economic benefits of anti-AGW measures in future, if we find that it was all a false alarm. Like I said, relax.
I’m gratified that you accept that your shrill economic doom-mongering is so hysterical.
What? It was previously believed that tropical forests would not be a big enough sink to get anywhere near counterbalancing deforestation effects. The report says that topical forests are, unexpectedly, a big enough sink to almost counterbalance such effects. Read it again.
“Scientists claim to have located the ‘missing carbon sink’ in tropical forests that are absorbing around one billion tonnes more carbon than previously thought.”
Would you like to repeat, once more, that “We do not know what the mechanism is, We simply lack that information. As scientists we therefore cannot talk about the mechanism.”?
Well, you are way out on a limb here so I understand your bunker mentality, but you’re not doing yourself many favours here IMO. Still, it’s only a message board.
The roughly 500 Gigatons of CO2 that human activity has released in the past few centuries. Do you accept this as even roughly accurate, or are you of the opinion that it is a gross overestimate?
Well, I’m struggling to think of another way to express it than “We’ve released 500 Gigatons of CO2, surely that must have increased the CO2 concentration given the sequestration rates in eg. intention’s graph?”
Actually, that’s not quite correct is it, intention? When the lines meet will be the point at which the total “excess” CO2 we have emitted will have been sequestered. The red line will flatten out earlier, when the orange line is as steep as the blue line. This is still a long way into the future, and will require what seems to me to be an unrealistically large increase in the sequestration rate, but does not require the orange line to bend until it’s almost vertical (and I hope even you think that that is an unrealistic extrapolation of the current “As atmospheric CO2 increases, so does the sequestration rate” regime!)
Also, intention, after some amateur (and possibly amateurish) digging around, I found this report which states at the bottom of page (iii) that “the rate of carbon absorption by terrestrial systems in the United States peaked around 1960 and has been falling since.”
Is this claim of an exception to the “as CO2 concentration increases, so does the sequestration rate” rule justified, in your opinion?
This claim is from a study that was actually done by a friend of mine, Joey Hackler. It can be found here.
In brief, the study is measuring something totally different from what we have been discussing. They estimated the changes in carbon emissions from the change in land use/land cover, called “LU/LC” in the trade.
To do this, first they estimated the amount of carbon in various kinds of land covers. So much for forest, so much for grassland, and the like. Then they estimated the amount of land with each type of cover in each year. Finally, they calculated the amount of carbon either emitted or absorbed by the process of changing one cover to the other. As you can imagine, the error bars on the study are quite large. In addition, the assumptions are somewhat tenuous. For example, if a forest is burned down, a different amount of CO2 is added to the atmosphere than if the same forest is logged.
Despite the large error estimates, I applaud their work, and use it in my own estimates of historical total CO2 emitted. However, it has nothing to do with what we are discussing, for two reasons. Let’s take forests as an example of the first reason.
Plants in general are “CO2 limited”. That is to say, their growth is limited by the amount of CO2 in the air. That’s why farmers pump CO2 into greenhouses … because plants grow faster if there is more CO2 in the air.
So how much CO2 does a forest sequester? Well, it depends on how much CO2 it is absorbing … and as the CO2 atmospheric concentration increases, so does the CO2 used by the forest. Note that, unlike in the work you cited, this does not involve the changing area of the forest. It is dependent on the atmospheric CO2 concentration.
The second reason that the work you cited doesn’t relate to our discussions is that chemical reactions in general are concentration dependent. Let’s take the amount of CO2 converted to limestone as an example. The higher the atmospheric concentration of CO2, the faster CO2 is converted to limestone. So once again, the sequestration is dependent on atmospheric concentration.
The fact that the overall sequestration rate has not been affected by the processes in the paper you cited is clear evidence that wherever the extra CO2 is being sequestered, it is the atmospheric concentration which is the main factor.
In fact, the Houghton/Hackler paper you cited gives a larger sequestration rate. This is because if we assume that our only additions to the atmosphere are fossil CO2, there is less CO2 to be sequestered. Once we add in the CO2 from LU/LC, however, it is obvious that there is more CO2 being sequestered than we had thought.
Not true. Emissions are still increasing. The CDIAC citation I gave above shows the emissions have not leveled off as of 2006, the latest data they have.
The amount sequestered will equal the amount emitted when the atmospheric CO2 level is high enough that the sequestration rate equals the emission rate. Assuming an e-folding time of 38 years, the sequestration rate is about 2.6%, that is to say that 2.6% of the atmospheric CO2 excess is sequestered annually.
Currently, we are emitting on the order of 8 GtC (gigatonnes of carbon) per year. This means that if emissions magically stayed stable at today’s rate, the eventual atmospheric excess burden will be 8/2.6%, or 308 GtC. Since 1 ppmv =2.13 GtC, this give an atmospheric excess of 145 ppmv. 145 ppmv plus the historical level of ~285 ppmv gives an equilibrium level of 285 + 145 = 430 ppmv.
However, there is no reason to assume that the emissions will stay at current levels, and every reason to think that they won’t. But how large will the increase be?
Well, since 1960 (see the CDIAC data I posted on Page 2 of this thread), the increase has been very linear at about 0.11 GtC per year. If this continues for 50 years (“business as usual”) and then levels off there, the eventual emissions would be 8 + 50*.11, or 13.5 GtC annually. This corresponds to an equilibrium CO2 level of about 530 ppmv … a long way from the feared 800 ppmv.
Finally, the current CO2 level is about 385 ppmv, so a doubling would put it at 730 ppmv. This means that in the extremely unlikely scenario that “business as usual” continues unabated, it will not result in a doubling of CO2 in the next one hundred years.
I hope this answers your question, if not, let me know.
Talk about that all you like, but until you have some evidence that they are all that is required then there’s for me to discuss.
Are you seriously asking if a fantastic example used for dramatic effect is more likely than the mechanisms you propose?
The problem is that we can’t demonstrate how much more likely. If yours have a correlation of 0.00005 and mine a correlation of zero there’s not a significant reason to believe either has any predictive power.
Bollocks. When it was pointed pout that current sequestration rates could be maintained by the missing sink that maintained high sequestration rate sin the past you responded “How, if there are fewer trees, more acidic oceans and all the rest?”
You were quite clearly arguing that it was impossible to maintain such rates because of fewer trees, more acidic oceans. Your objection relies on your insistence that you insist that it must solely involve forests, soil, plankton and limestone.
And you think that’s alright? Since you are proposing removing people’s rights and restricting their freedoms you better have a damn lot more than “it’s possible it might work out OK” if you want my support. You’d better have iron clad facts to support your assertions.
Umm, do you understand that would and could are different words?
How the hell does this support your claim that global forest cover was higher at the timeof the last glacial maximum? Did you even read it? It only goes back 15 years. In case youa re unaware the last glacial maximum was little longer ago than 1995.
Nonsense. The historic low point was 1600, not 1800. 1600 was unambiguously lower than 1800.
But the important point is that you have conceded that you are unable to identify any difference in the trend from 1600-1750 from the trend for 1750-200, despite proclaiming loudly that humans have made a difference to the trend.
I have no idea. Nor do you.
Ahh, that’s what you meant.
So what is your point? That we can’t trust the pre-Mauna Loa data? That we have absolutely no idea of CO2 levels for pre-1960.
I now have no idea what point you are trying to make here? In your OP you noted the CO2 level in past millennia as though it was relevant. Now you seem to be saying that it is untrustworthy and irrelevant.
Where are you going with this criticism of the pre-1960 CO2 levels?
Huh? Are you even following your own argument? You stated that the current lag between CO2 and temperature was different “Compared to the clear and obvious temperature rises that preceded the CO2 rises in the past”. I asked how you know that, and you claim that I said it was different.
Bollocks. I never said any such thing. I honestly think that you have lost track of the argument that you yourself are trying to make here. Every post certainly seems to suggest that.
And I ask for the 6th time: How do you know that the current lag between CO2 and temperature was different “Compared to the clear and obvious temperature rises that preceded the CO2 rises in the past”?
What’s your point here exactly? Once again you seem to have lost track of your own argument. You are arguing that that this time the atmospheric CO2 can’t be sequestered rapidly because it comes from buried carbon. This is a claim for which you have absolutely no evidence in a field in which there are massive uncertainties about the basic mechanisms.
At no stage did anyone suggest that there is no evidence that humans haven’t burned fossil fuels. What you have been called on is your claim that the mechanisms that rapidly sequestered gigatonnes of CO2 in the past won’t work this time because the CO2 comes from fossil fuels.
So put the fricken’ straw man to bed and try to follow your own argument will you.
Yeah, I’m sure evidence of benevolent aliens would put your mind at rest too.
I thought we having a debate about, you know, plausible science based on fact. Apprently I am but you are not. You want a debate on things that have never happened and as far as we can tell can never happen.
Can’t help you there.
No.
Oh FFS how many times do I have to post this:
** We do not know what the mechanism is, We simply lack that information. As scientists we therefore cannot talk about the mechanism. It’s not a case of reluctance. It is a case of lacking sufficient information to engage in this conversation.**
We do know that gigatonnes of CO2 have been rapidly added to the atmosphere numerous times in the past and that this has had no long term impact on CO2 concentrations. We know this lack of impact was because of some massive, rapid sequestration mechanism that removed the CO2 almost as rapidly as it was added.
The atmosphere neither knows nor cares where those gigatonnes of carbon came form. It doesn’t care if it comes from volcanoes or fossil fuels or forest fires. I really don’t; think that you understand this point. CO2 is CO2. It’s chemically identical regardless of source.
I neither know not care. It’s total red herring, as I’ve pointed out numerous times.
And your point in quoting this would be would be what? You made a claim which has no basis in evidence, when I pointed out that exactly the opposite could conclusion could be equally true base don the evidence you constructed massive strawman. How does any of this prove otherwise?
If you like. I neither know nor care. When you have coherent argument bring it back here.
How does that happen? How does someone whose family has lived on the land for 20, 00 years who has been forced to move ot the city and take a job labouring that they hate get back the enjoyment of their youth in 50 years time.
This is nonsense.
Gees, more straw.
What doom mongering? Can you give me an example of where I said that anything is doomed? I don’t think anything is doomed. I do think that it’s immoral, unjust and unethical to remove people’s rights when you have no facts, but I don’t think anything is doomed.
The doomsaying is entirely your province my friend.
I think you need to read it again. I also think you need to understand that for forests to be a net sink they need to absorb more carbon than they emit. When the absorption from growth is less than the emmissions from loss then hw can they be a sink? That’s just fucking stupid.
Sigh. “Net sink”, “pool” and “flux”. Learn these terms.
Do I need to. If you still don’t understand this then I certainly will.
Yep, an argument ad populum. Consider me convinced.
I neither know nor care. The whole thing is massive red herring.
Yep, that’s good science. I must have happened, therefore I believe it.
Look, SentientMeat, I’m on the verge of giving up on you. You are clearly struggling to even follow your own argument here. Half of your posts aren’t even making sense. Your facts have been shown to be incorrect from the very first post.
And at the end all you can say is ““We’ve done x, surely it must have resulted in y” and “ I want evidence that something that has never happened before will magically happen now”. You have no evidence at all, despite my asking you to present this evidence time and again.
If you have anything to add in terms of facts or a coherent argument or facts then lay it out clearly in your next post. Trying to snip quote my posts is clearly leaving you confused and struggling to follow your own argument, much less mine.
If you can’t do that I’ll bow out. The fact is that CO2 levels have not been stable for millennia as you claim. The fat is that forest cover was not higher at the last glacial maximum, as you claim. The fact is that the planet has rapidly sequestered gigatonnes of CO2 from the atmosphere many, many times in the past. The fact is there is no reason to believe it isn’t doing so again this time. And the fact is that you cannot demonstrate any human impact on the pattern of increase of atmospheric CO2 levels.
Lets get back to basics. The fundamental difference between Blake and SentientMeat seems to be whether burning fossil fuels has increased atmospheric CO2. Am I reading this correctly?
If so, I’d say the answer is yes. Now, it is true that increasing temperature increases CO2. But ice cores indicate a couple of things.
First, they indicate that there are other forces at play. The Vostok cores indicate that during the period from 5000 to 4000 years ago, the temperature dropped by one degree, but the CO2 went up from about 260 ppmv to 280 ppmv. Why? No one knows.
Second, they can give us a rough idea of the relationship between temperature and CO2. According to the Vostok cores, an increase of 0.6°C (the 20th century change) is associated with a change in CO2 of only about 10 ppmv, much less than is observed.
Of course, this leads to another puzzle. During the ice ages, a 100 ppmv change in CO2 is associated with about a 10°C temperature change … which casts huge doubt on the idea that the changes in CO2 are causing temperature change. It also supports my claim that there is a cap on the global temperature.
Making pop psychology observations about entire groups of people, particularly when pointed at posters in this forum, are not useful and have no business in these threads.
